Biochemical analysis of Entamoeba histolytica HM1 strain resistant to complement lysis.

In this study, quantitation of several hydrolases and analysis of electrophoretic patterns of E. histolytica HM1 axenic strain periodically exposed to lytic-human serum (lytic-HS), heat-inactivated human (HI-HS) or bovine (HI-BS) sera were performed. The N-acetylglucosaminidase (NAGAse) levels increased in amebas resistant to complement. The acid phosphatase (AP) and proteolytic activity (PA) levels did not vary significantly in all groups of treated amebas, as compared with amebas from axenic cultures. Moreover, amebas exposed to either HI-HS or lytic-HS sera showed a discrete quantitative increase as compared with HI-BS group, in some peptides with a M(r) between 116 and 45 kDa. These results indicate that, besides resistance to complement lysis, exposure of E. histolytica to lytic-HS induces an augmentation in NAGAse levels.